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A possible solution might be to put restrictors directly on the cylinders. Thus lowering the risk by eliminating the hose as a factor. (would still be a factor, but should not slam shut in the event of a hose break) Just a thought.
Ben Schneider
Ed Anderson <eanderson@carolina.rr.com> wrote: Hi Ben, good question concerning safety. The door hydraulic cylinders are single acting push-only. A restrictor valve holds the door open and a push of a button opens the value to let the fluid back into the tank thereby lowering the doors. The doors do not slam down but do come down within 10-15 seconds (will have to time and
see exactly how long it takes). But, regardless of double acting or single acting if a hose breaks you could be in trouble as you suggest. I intend to have 9-10 foot pipes attached to main beam that when the door is open, I can pull down and set to hold the door up. That way should a hose fail the door won't slam down. These are 4000 psi bursting lines with 450 psi maximum pressure - so hopefully I am not over stressing them. It could certainly ruin your day to have that door come down on you. Thanks for mentioning it - safety is always a high concern. Ed ----- Original Message ----- Sent: Sunday, August 13, 2006 8:25 PM Subject: [FlyRotary] Re: Emailing: DoorOpenLside.jpg
Ed,
A question out of curiosity, Do you have the hydraulics set up so that the door is power up, and power down, or is it just gravity down? Reason I ask is in the event of a hose or pipe break, that the door does not come crashing down. That it would stay in place, or at least a restrictor so as to let the door down very
gently. Because, if your luck is anything like mine, the airplane would likely be passing under it at the time. Not to mention the safety issue. Just curious. Personally, I think the hydraulic single panel door is the only way to go, provided it is done safely. Just my opinion.
Ed Anderson <eanderson@carolina.rr.com> wrote: Hi David,
You are right on all counts, fortunately- it is not a timber beam. Its
actually a engineered box beam very similar to wooden spars built for
aircraft. But, without quite as much attention to weight savings {:>). I
used Liquid Nails Subfloor adhesive after discussing my project/needs with
their technical staff (learned a bit about wood glues/adhesives) and deck
screws to build the beam. It weighs around 180
lbs.
Its basically a warren truss enclosed in plywood. It just took less work
(more lumber, but less work), to have the building material store cut me 16"
wide strips of plywood (4 to a sheet) and then use those as the webs rather
than cutting out the gussets necessary for each brace/flange interface to
build an wooden open warren or Pratt truss. It would be interesting to see
how light the beam could be made, but I've been working on building hangars
and doors since around March and wanted to see the light at the end of the
tunnel {:>). Besides, I can't fly until the door is finished as my aircraft
is trapped inside!!!
Appreciate your comments
Ed
----- Original Message -----
From: "david mccandless"
To: "Rotary motors in aircraft"
Sent: Sunday, August 13, 2006 6:23
PM
Subject: [FlyRotary] Re: Emailing: DoorOpenLside.jpg
> Hi Ed,
> I do not need a door nor a hangar, but as the discussion progresses I am
> becoming more interested.
> I would have thought that a Warren type truss, fabricated from, say, 3
> inch channel for chords and 2 inch angle for webs, would have been a
> better and lighter solution than a timber beam.
> Is that big center beam a laminated truss or a plywood fabricated beam?
> I am an old structural engineer from 40 years ago, I have a lifelong love
> of bridges, and have never loss my interest in beams etc, so this is not
> meant to be criticism but rather to satisfy my own curiosity.
> BR, Dave McC
>
> On 14, Aug , at 5:51 AM, Ed Anderson wrote:
>
>> I am convinced (but have not done a comparative analysis) that this
>>
arrangement does produce less outward force on the top of the door
>> frame/hanger than a bi-fold. The hydraulic ram ends up at a 47 deg angle
>> to the ground and so supports approx 70.7 % of the door weight. If the
>> door weighed 600 lbs finished then I estimate the door frame would
>> support approx 200 lbs and the ram 400 lbs. Since the "balance" point of
>> the door is along the axis of the beam this should mean very small
>> outward forces once the beam is raised.
>
>
> --
> Homepage: http://www.flyrotary.com/
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>
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